Method and structure for eliminating corona discharge in high voltage electron discharge devices

ABSTRACT

A high voltage electron discharge device, such as the horizontal output tube for a color television receiver, has a getter assembly electrically and mechanically connected to the anode whereby the getter is maintained at anode potential.

ilitefi 111m Patent 1191 Field of Search; ..3 l 3/ 178 Allgaieir 1 1 Apr. W, 1973 [54] METHOD AND STRUCTURE FOR [56] References Cited ELHWNATHNG CORONA DESCRGE 1 1N 111G111 VOLTAGE ELECTUN UNITED STATES PATENTS DISCHARGE DEWCES 2,418,390 11/1947 Atlee ..313/178 Inventor: Wmim A. Angaier, Empodum Pa. 3,080,498 3/1963 Hammond et a1. ..3l3/l78 ,[73] Assign ee: GTE Sylvania linenrantecll,Seneca Primary Examiner Roy Lake N Assistant ExaminerDarwin R. Hostetter [22] Filed: 'Oct. 21, 1971 Attorney-Norman J. OMalley et al.

, l. N 191 PP 0 ,395 [57] STRACT e I A high voltage electron discharge device, such as the [52] US. Cl .313/178 horizontal output tube for a color television receiver, [51] 1111.0; .Jiilllllj 19/70 has a getter assembly electrically and mechanically connected to the anode whereby the getter is maintained at anode potential.

1 Claim, 2 Drawing Figures PAIElHmAPRIOHH 3,727, 0

INVENTOR. WILLIAM A. ALLGAIER jJo ' ATTORNEY METHOD AND STRUCTURE FOR ELIMINATING CORONA DISCHARGE-IN ll-IIGII VOLTAGE ELECTRON DISCHARGE DEVICES BACKGROUND OF THE INVENTION connection, instead of being located in the stem or base of the device with the remaining leads, emerges'from the top of the device envelope where it is sealed in the glass thereof and connected to a cylindrical metal cap. Electrical connection to a desired circuit is made by fitting a connector to this cap. Previously, this type of device utilized a side mounted getter, below the top mica. This resulted in the flashed-getter material being deposited on the sides of the bulb envelope in the area of the anode, and acted as a mirror, preventing heat radiation from the device. The loss in heat radiating capability of the device led to excessive anode heating with consequent loss of reliability, especially when the device was operated at or near its maximum design ratings.

In an attemptto solve this problem it was suggested that a top flashed getter be employed; i.e., one which flashed into the dome of the device. This type of getter capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above-described drawings.

Referring now to the invention with greater particu- 5 larity, there is shown in FIG. 1 an electron discharge device 10, such as can be used as the horizontal output tube of a color television receiver. Device has an evacuated envelope 12, generally of glass, and contains an electrode cage 14 which includes at least an anode 16, a cathode I8 and a getter assembly 20. Device 10 is a type of high voltage tube utilizing a top cap 22 for the anode connection. An anode lead 24 is sealed into the upper dome of the envelope l2 and is electrically connected at one of its ends to the top cap 22. The other 7 end of the lead 24 is'connected to the anode as will be was connected generally to one of the beam plates of the tube. While solving the heat radiating problem, it. was found that a new problem was introduced. When such devices were run with an anode voltage aslow as 5,000 V. a visible corona discharge developed at the outer edges of the top cap. This corona discharge severely damaged the glass about the-seal with the result that the device eventually became defective.

OBJECTS AND SUMM RY or THE INVENTIO It is therefore, an object of the invention to obviate the disadvantages of theprior art.

It is another object of the invention to enhance the operation of high voltage electron discharge devices utilizing a top cap.

It is another specificobject of the invention to provide such a device that eliminates problems caused by corona discharges withoutupsetting the necessary heat radiating characteristics of the device.

Theseobjects are accomplished in one aspect of the invention by the provision of device of the type described above wherein the getter is mounted above the top. mica, near the dome of the envelope, and is maintained at anode potential.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention,

together with other and further objects, advantages and described hereinafter.

The electrodes of the cage 14 are held in spaced relationship by upper and lower micas as is conventional in the'art. In this particular instance only upper mica 26 is shown. The micas are held in place by various tabs or ears such as tabs 28 of anode 16 which are twisted or otherwise deformed after being inserted through the micas to maintain the micas in the proper location.

'The getter assembly 20 comprises a supporting bracket 30 which is substantially semi-circular in configuration and whose ends 32 and 34 are electrically and mechanically connected to tabs 28 of anode 16. The upper portion of the support 30 has affixed thereto an upstanding electrically conductive member 36 which is connected to anode lead 24. Also affixed to support30is atleast one getter flat 38; however, two are shown in the drawing.

A tube made as described above obviates the disadvantages of the prior art. By eliminating the getter flash from the side wall of the envelope, heat radiation is increased, and by maintaining the getter at anode potential deleterious corona discharge is eliminated.

- In FIG. 2 is shown an alternate form of getter support bracket 40. Herein, the support is substantially U- shaped but having a flattened bilght 42. The radius 44 joining the leg portions 46 with the bight 42 should be as large as reasonably possible to further reduce any possibility of corona discharge. Such a design can be utilized in smaller tube sizes where the space between the dome and the top mica does not allow the bracket 30 to be employed.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claim.

What is claimed is:

I. A high voltage electron discharge device incorporating means for eliminating corona discharge having an evacuated envelope containing an electrode cage comprised of at least an anode, a cathode and a getter assembly, said anode and cathode being positioned between a pair of insulating micas with said micas maintaining a force fit within said envelope, said anode having at least two projecting tabs extending upwardly through one of said micas; said getter assembly providing said means for eliminating said' corona discharge and comprising a generally U-shaped bracket electrically and mechanically connected to said pair of and mechanical connection to said anode lead whereby, when flashed, the gettering material shall be deposited upon the inner upper surface of said envelope surrounding said anode lead. 

1. A high voltage electron discharge device incorporating means for eliminating corona discharge having an evacuated envelope containing an electrode cage comprised of at least an anode, a cathode and a getter assembly, said anode and cathode being positioned between a pair of insulating micas with said micas maintaining a force fit within said envelope, said anode having at least two projecting tabs extending upwardly through one of said micas; said getter assembly providing said means for eliminating said corona discharge and comprising a generally Ushaped bracket electrically and mechanically connected to said pair of tabs on said anode and having at least one getter attached to said bracket and formed to flash upwardly; an electrical anode lead being sealed in the upper end of said device opposite the leads for said cathode; and means attached to said bracket for making electrical and mechanical connection to said anode lead whereby, when flashed, the gettering material shall be deposited upon the inner upper surface of said envelope surrounding said anode lead. 